Veteran pollster Frank Luntz said on "The Kelly File" that his
focus group had overwhelmingly named Cruz as the winner of the
Fox Business Network debate.

Luntz started by playing a clip of
a feisty exchange between Cruz and real-estate mogul Donald
Trump over the Texas senator's eligibility to be president.

"This is truly the highlight of the debate," Luntz said.

Trump
argues that Cruz's birth in Canada could disqualify him from
the Oval Office because the Constitution requires presidents to
be "natural-born" citizens. Cruz argued that his American mother
meant he was a US citizen at birth and thus eligible for the
presidency. Many legal scholars agree with Cruz.

"I would suggest we focus on who's best prepared to be
commander-in-chief, because that's the most important question
facing the country," Cruz said in the clip.

After Trump said there great legal scholars who thought Cruz
could be disqualified, Cruz touted his legal background as Texas'
former solicitor general.

"I've spent my entire life defending the Constitution before the
US Supreme Court, and I'll tell you, I'm not going to be taking
legal advice from Donald Trump," Cruz said as the audience roared
in approval.

Almost everyone in Luntz's focus group apparently thought that
Cruz had schooled Trump on the issue.

"He handled him," one of the focus group's participants said of
Cruz. "It was really evident that he was capable of taking the
hit and handling it, and turning Donald around on himself."

"Not only that," a man added. "He was very eloquent, very
level-headed about everything that he had to say tonight. I like
Donald Trump. Donald Trump is very opinionated, which doesn't
make it easy for him during the debate."

Watch below:

According to Luntz, two other debaters also had a strong night
Thursday: Sen. Marco Rubio of Florida and Gov. Chris Christie of
New Jersey.

The focus-group participants praised Rubio for defending gun
rights and Christie for railing against President Barack Obama.